1. Field of the Invention
This invention generally relates to tools used in oil and gas wellbores. More specifically, the disclosure relates to expansion apparatuses used to anchor downhole tools in wellbores.
2. Description of Related Art
In drilling or reworking of oil wells, a great variety of downhole tools are used. Such downhole tools often have to be anchored within the wellbore for proper operation. For example, but not by way of limitation, it is often desirable to seal tubing or other pipe in the casing of the well, such as when it is desired to pump cement or other slurry down the tubing and force the cement or slurry around the annulus of the tubing or out into a formation. It then becomes necessary to seal the tubing with respect to the well casing and to prevent the fluid pressure of the slurry from lifting the tubing out of the well or for otherwise isolating specific zones in a well. Among other tools, packers are designed for these general purposes. Packers use an expandable sealing element to seal the tubing; however, these elements cannot generally provide sufficient anchorage to prevent lifting of the tubing. Typically, packers have thus relied on slip rings which expand to grippingly engage the wall to anchor the tubing. Additionally, anchoring is needed for application of other downhole tools within the wellbore.
Problems are encountered in anchoring downhole tools because of variation in wellbore or casing diameter. Thus, an anchor that adequately expands for one size casing might be too small for a larger size casing or too large to fit into a smaller casing. This can be especially problematic where a downhole tool must be lowered through the smaller casing and anchored in a larger casing below the smaller casing.
Thus, while there are a number of anchoring apparatuses available, there is a need for further such apparatus that can meet the needs of different well operations utilizing different casing sizes.